Watch any movie about the years of prohibition, and you’ll probably see character gain admittance to a speakeasy by using a secret knock on the door. In the old movies, a little sliding door would open so the doorman could check you out and let you in. With [IsmailSan’s] electronic lock, the secret knock automatically unlocks the door. You can see a video of how it works, below.
(Ed Note: Grrr…GitHub repo got pulled between writing and publication. Go check out the in-links in the bottom paragraph if you’re interested in knock-detectors.)
The device uses a piezoelectric speaker to detect the knocking. A speaker is a transducer and like many transducers, it will work — to some extent — in either direction. A servo motor manages the deadbolt. An Arduino runs the whole thing.
Continue reading “Secret Knock Unlocks Door”
Pressing the power button on your computer usually isn’t too much trouble, unless your computer is stored away somewhere hard to reach. [Joonas] has been hard at work on a solution that would also impress his friends, building a knock sensor to turn on his PC.
For around $10 in parts he put together an ATTiny45 that emulates a PS/2 device, which takes advantage of his computer’s ability to boot upon receiving PS/2 input. The build uses a Piezo buzzer and a 1M Ohm resistor as a knock sensor exactly as the official Arduino tutorial demonstrates, and one of those PS/2-to-USB adapters that are most likely lurking in the back corner of every drawer in your office.
[Joonas] used AVRweb to disable the 8X clock divider so there’d be enough clock cycles for PS/2 communication, then loaded some test code to make sure the vibrations were being detected correctly. You can check out his Github for the final code here, and stick around after the break for a quick video demo. Then check out a similar hack with [Mathieu’s] home automation knock sensor.
Continue reading “Turn A PC On With A Knock And An ATTiny”
[Paul Mandel] just finished building this knock box project. It’s a familiar concept that uses a solenoid to tap on the side of the box. The Arduino driven setup monitors vibrations on the lid. When you knock on the box, it records the pattern and plays it back using the solenoid.
He was inspired by a knock-detecting door lock. Using that code as the starting point he implemented a system that takes input from a simple push button and echos back the rhythm using the Pin 13 LED on the Arduino board. This is a great way to start as it removes the complexity of driving a solenoid and monitoring a piezo element. After a bit of success he implemented each of those hardware modules one at a time. You can get a look at the final product in the clip after the break.
One of our favorite version of this project is still the knock block from several years back.
Continue reading “Wooden Box Repeats Rhythm Used When Knocking On The Lid”
Clap On!… Clap Off!… was super awesome when The Clapper came out in the mid-eighties. Now [Mathieu Stephan] is trying to make the concept much more functional. He put together a controller that lets you knoch on walls to control things around the house. It’s called the Toktoktok project and uses small boxes to receive user input and control items like lamps and computers.
A piezo element picks up the noises made by a user. Above [Mathieu] demonstrates how sensitive the element is, picking up scratching and knocking anywhere along this wall and displaying it as a waveform on the computer monitor. Clever processing and filtering of these noises lets the device convert them into different commands. He covers all of this in the video after the break, then demonstrates a bunch of functionality such as waking up and starting audio playback from a computer just by tapping on the coffee table.
This isn’t the first time we’ve seen the concept. One of our favorites is this door lock which listens for the secret knock. But [Mathieu] is trying to extend the functionality and bring it to a more general market. Continue reading “Reinventing The Clapper With A Knock-based Home Automation Controller”
Many people have touch-screen devices, however, this hack claims to be the first picture frame to feature a “no-touch” interface. Although someone somewhere certainly has a digital picture frame hooked up to a “Clapper”, we’re going to give [Wasabi] the benefit of the doubt.
After buying a Microtouch kit from Adafruit several months ago with the intention of building something meaningful, [Wasabi] ran into a common problem among hackers, a lack of time. Instead of totally giving up on the device, the decision was made to make it into a simple picture frame. Although the Microtouch features a touchscreen, it also features an accelerometer. With a little hacking, as described in his write-up, the “touchless” picture frame was born. Cleverly, the screen was hidden behind glass, but through this interface, interaction was still possible.
The device itself seems like a great hacker tool, especially at a price point of just under $70. Here’s a hack where “Zork” was ported to this device, but be sure to send us any other projects you come up with using it! Check out the video after the break of this device in action!
Continue reading “A No-touchscreen Picture Frame?”
[Steve] shows us his version of the knock detecting lock system. The idea is pretty simple, knock in a certain pattern and the door unlocks. We’ve seen it before several times. This solution is somewhat cleaner than the others, not only in physical design, but also in how you reprogram it. Simply push the reprogram button and enter your new knock. We’re a bit surprised that the suction cups actually hold it on the door. Maybe it’s just us, but we can never seem to get those things to hold very well. There are lots of great pictures as well as the source code available on his site.